Date of Award

3-24-2022

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics and Astronomy

First Advisor

Gregory Guisbiers

Abstract

Nanoscience and nanotechnology are some of the fastest growing fields of materials science that have given impact to several fields of science including biology, medicine, and catalysis. These applications take advantage of several properties of nanoscale materials that are present at sizes below 100 nm namely the increased surface to volume ratio. From a theoretical point of view, nanoscience research is dominated by Density Functional Theory and Molecular Dynamics. These techniques dominate for good reason, but are not without their own limitations due to their computational complexity which results in very long calculation time to complete on materials whose size is greater than ~10 nm. Nano-thermodynamics is a complementary technique to answer fundamental questions theoretically and has shown great accuracy in predicting several materials properties of materials from bulk sizes to sizes around ~4 nm. In this dissertation, the nano-thermodynamics framework is presented and used on three binary nano-alloys: Cu1-xPtx, Bi1-xSbx, and Se1-xTex. In the Cu1-xPtx alloy system, a feature is predicted in its nanophase diagram suggests a transition from a substitutional alloy to an interstitial one. This prediction is confirmed experimentally. In the Bi1-xSbx system, the nanophase diagram is predicted. The results support the idea of a non-enhanced miscibility at the nanoscale which is similar to what is predicted via other techniques for other alloy systems. Additionally, the surface segregation index is introduced. The predicted phase diagrams are confirmed with respect to experimental data in the literature. In the Se1-xTex system, the full phase diagram are predicted at the bulk and nanoscale. In particular, machine learning techniques are used to classify the temperature-composition space for the glassy and crystalline transitions in the Se1-xTex alloy system. Additionally, the systems optical properties are evaluated at the bulk scale and predicted at the nanoscale. Moreover, the optimized range of particles and sizes are suggested for this. Additionally, a model to determine the limit of nano-thermodynamics in predicting the energy bandgap of nanomaterials is described and assessed. The results here in provide a roadmap for the synthesis, application range, and properties of the alloys studied.

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